Scientific and reasonable water and fertilizer regimes positively affected crop growth, yield, fruits quality and soil environment improvement. As a liquid quick-acting organic fertilizer to substitute chemical fertilizers, biogas slurry has been widely used in agricultural production. However, the lack of research on the proper comprehensive quality evaluation model and irrigation mode under biogas slurry limits the promotion and large-scale application of biogas slurry in agricultural production. In this study, three biogas slurry (BS) ratio (1:4BS, 1:6BS, 1:8BS; volume ratio of biogas slurry to water), three irrigation levels (W1, W2, W3) and three fertilizer control treatments (CF1, CF2, CF3) were conducted in field experiments. Eleven single indexes from four type qualities (external quality, taste quality, nutrition quality, storage and transportation quality) were adopted to establish the comprehensive evaluation index system of tomato. The principal component analysis, grey correlation analysis, membership function analysis and TOPSIS analysis model (based on the combination of objective entropy method and subjective analytic hierarchy process) were used to estimate the comprehensive quality of tomato fruits. Moreover, the objective combination evaluation mode based on overall diversity was used to evaluate the results obtained from the four independent comprehensive evaluation methods. The aim is to mitigate inconsistencies of multi-attribute evaluation models. The results showed that biogas slurry application was beneficial to the accumulation of aboveground biomass under the same irrigation amount, which can effectively improve the sugar to acid ratio and lycopene content of tomato. T3 (1:4BS, W3) and T1 (1:4BS, W1) obtained the highest yield and water use efficiency (WUE), respectively. The results of Kendall consistency test and Pearson correlation coefficients showed that there were good compatibility and high consistency among the four independent comprehensive evaluation models, and the combined quality evaluation model can be performed directly. As the correlation coefficients between combined evaluation model and each of four independent methods reached 0.965, the combined evaluation model was capable of reducing the differences of four independent comprehensive evaluation model. The combined quality evaluation results showed that T2 (1:4BS, W2) recommended strongly in this study could effectively improve the yield, quality and WUE of tomato.

Reasonable techniques and methods in biogas slurry application are significant for the promotion of biogas slurry and the improvement of crop quality in agricultural production. To investigate the impacts of different biogas slurry application techniques on the water use efficiency, growth, yield, and quality of tomatoes, three irrigation techniques, and two application methods were considered in this study. The three irrigation techniques are alternate partial root-zone irrigation (APRI), fixed partial root-zone irrigation (FPRI), and two sides root-zone irrigation (TSRI). Two application methods refer to applying the biogas slurry with hole irrigation and surface irrigation. In addition, principal component analysis (PCA) and technique for order preference by similarity to ideal solution (TOPSIS) methods were adopted to evaluate the comprehensive quality and comprehensive indicators of tomatoes among different treatments. There are three hole irrigation treatments, T1 (APRI), T2 (TSRI), T3 (FPRI), and three surface irrigation treatments, T4 (APRI), T5 (TSRI), and T6 (FPRI) were set in two-season pot experiments. The results show that the plant height, dry matter accumulation, fruit yield, and water use efficiency present a similar descending trend for APRI, TSRI, and FPRI under the same methane irrigation method, yet show that the hole irrigation treatment was higher than the surface irrigation treatment for the same irrigation technique. These indicate that the coupling of APRI technique and hole irrigation is more conducive to the increase of plant production and water use efficiency. Meanwhile, T1 treatment can significantly improve the soluble sugar, sugar-acid ratio, VC content, soluble protein, soluble solid content, and firmness of tomato fruits, which are better for the taste, storage, and transportation of tomato fruit. The titratable acid content in tomato fruit is the highest in T2 treatment, followed by T5 treatment, indicating that TSRI technique may result in an accumulation of titratable acid and is not conducive to the taste of the tomato. The comprehensive nutritional quality and index evaluation results show that T1 treatment ranks the highest among all treatments, and can be used as an optimal irrigation method for the implementation of integrated water/biogas slurry. Keywords: biogas slurry, irrigation technique, coupling, quality evaluation, comprehensive index evaluation DOI: 10.25165/j.ijabe.20221505.6901 Citation: Zheng J, Qi X Y, Yang S H, Shi C, Feng Z J. Effects and evaluation of biogas slurry/water integrated irrigation technology on the growth, yield and quality of tomatoes. Int J Agric & Biol Eng, 2022; 15(5): 123–131.

An experiment was conducted in spring 2024 to investigate the effects of biochar, biogas slurry, and dicyandiamide (DCD) on N₂O emissions from soil in protected tomato cultivation. Five treatments were applied: conventional fertilization (CK1), biogas slurry alone (CK2), biochar combined with biogas slurry (T1), DCD combined with biogas slurry (T2), and the combination of biochar, biogas slurry, and DCD (T3). The study aimed to assess the response of the soil physicochemical properties and nitrifying ammonia-oxidizing microorganisms in the tomato root zone to these treatments and to determine their impact on soil N₂O emissions. The results showed that adding biochar and biogas slurry increased the soil pH, organic matter content, and levels of nitrate-N and ammonium-N, without affecting ammonia-oxidizing archaea (AOA) but inhibiting ammonia-oxidizing bacteria (AOB). The inclusion of DCD raised the soil pH and ammonium-N levels, enhanced AOA growth, did not alter organic matter content, and significantly reduced nitrate-N levels and AOB activity. Compared to CK1, treatments CK2, T1, T2, and T3 decreased the average N₂O emission flux by 5.83%, 8.24%, 15.27%, and 16.16%, respectively. The application of biochar, biogas slurry, and DCD enhanced the physicochemical properties of the root zone soil and notably reduced N₂O emissions in protected tomato cultivation, with T3 showing the most effective results. The biochar and biogas slurry used in this study, both derived from agricultural waste, promote sustainable agricultural development and enhance economic benefits. However, this study only considered the short-term effects of biochar, biogas slurry, and DCD, necessitating further research to explore their long-term impacts and mechanisms.

To investigate the coupling effects of biochar and nitrogen fertilizer on tomato growth, nitrogen uptake and utilization (NUU), and the soil environment, a pot experiment was conducted using ¹⁵N-tracing technology from March to July 2021 and from September 2021 to January 2022. Three biochar application rates (B0, B1, and B2; 0, 3, and 6 t/hm², respectively) and three nitrogen levels (N1, N2, and N3; 150, 300, and 450 kg/hm², respectively) were set up. The results show that the growth, yield, rate of ¹⁵N uptake, nitrogen derived from soil (Ndfs), total nitrogen (TN), ¹⁵N utilization, and recovery rate of tomatoes were improved under biochar application, but nitrogen derived from fertilizer (Ndff) gradually decreased. A Pearson correlation analysis showed that the ¹⁵N uptake, Ndfs, TN, rhizosphere soil organic matter, soil organic carbon, and TN were significantly positively correlated with the yield and lycopene content of tomatoes. The comprehensive benefit to the tomatoes was evaluated based on combination weighting with the help of the technique for order preference by similarity to ideal solution (TOPSIS). This indicates that the best planting mode was the B2N2 treatment, with a biochar rate of 6 t/hm² and nitrogen levels of 300 kg/hm², under the alternative partial root-zone irrigation.